The present invention relates to rotating union coupling devices which have particular application in high temperature environments employing steam, hot water and hot oil applications.
Rotating unions have been used extensively in the paper, plastic and textile processing industries to couple the outlet of a fluid source to rotating drums or cylindrical rolls or to open gear paper machines. In known rotary unions utilized in coupling fluid sources to such rotating devices, the rotary unions utilize either carbon journal bearings or dual ball bearing structures to absorb and maintain the alignment of the rotor and the load of the joint assembly. However, such ball bearing assemblies are limited to a maximum temperature range of about 125.degree. C. because of the thermal instability of the standard bearing materials above such temperatures. Also, when ball bearings assemblies are utilized as the rolling bearing structure within a rotary union, the ball bearing assembly must be grease lubricated which effectively limits the use of such bearing structures to application temperatures dictated by the bearing temperature limitations. Additionally, such ball bearing assemblies can be lubricated by the heat transfer oil, which is a relatively poor lubricant, and require that the assembly include at least dual bearing structures to provide support for the rotating rotor in the rotating union.
Another use of ball bearing structures in rotary union assemblies requires multiple seal assemblies and external buffer systems to maintain the thermal stability of the carbon bearing materials. Accordingly, such bearing structures are expensive and space consuming. Thus, when it is desired to provide rotating union assemblies capable of use at high temperatures and which include a simplified structure, such bearing assemblies have found limited application.